#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int Fact(int x)
{
	if (x == 0)
	{
		x = 1;
	}
	else{
		x = x * Fact(x-1);
	}

	return x;
}




int main()
{	
	int Fact();
	int n = 0;
	scanf("%d", &n);

	int r = Fact(n);

	printf("%d", r);

	return 0;
}